A-LevelMathematicsProbability and statistics9709/62 · Oct/Nov 2021 · Q16 Marks
The mass, in kilograms, of a block of cheese sold in a supermarket is denoted by the random variable M. The masses of a random sample of 40 blocks are summarised as follows. n = 40 Σm = 20.50 Σm² = 10.7280
- (a)Calculate unbiased estimates of the population mean and variance of M.[3]
- (b)The price, $P, of a block of cheese of mass M kg is found using the formula P = 11M + 0.50. Find estimates of the population mean and variance of P.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [B1] 0.5125
- [M1] (40/39)(10.728 - (20.5^2)/40) or (1/39)(10.728 - 20.5^2/40)
- [A1] 0.0056859 or 0.00569 (3 sf) or 887/156000
- [B1 FT] [11 × '0.5125' + 0.5]) = 6.1375 or 491/80 or 6.14 (3sf)
- [M1] 11^2 × '0.0056859'
- [A1] 0.688 (3sf)
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